title: Ferredoxin excreted from photosynthetic bacterium, Rhodospirillum rubrum: purification and properties.
abstract: When the photoheterotroph, Rhodospirillum rubrum, was grown in the light, ferredoxin was excreted from the cells in a significant amount, as well as hydrogenase. The extracellular ferredoxin was purified to a homogeneous state. The molecular weight was approximately 9,000, and the oxidation-reduction mid-potential was -0.29 V (N=1) at pH 7.0 and 25 degrees C. The amino acid composition was different from those of the intracellular ferredoxins, which were already known. The contents of non-heme iron and acid-labile sulfur were 10.6 and 7.9 mol/mol protein, respectively. The extracellular hydrogenase catalyzed the evolution of hydrogen gas from the ferredoxin in the reduced form. The Km for the ferredoxin was 4.1 micro M, one-seven hundredth as low as that for methyl viologen. There is a possibility that hydrogenase here were functional for evolution of hydrogen gas outside the cells.
mesh_terms: D000596:Amino Acids; D055598:Chemical Phenomena; D002621:Chemistry; D005288:Ferredoxins / Q000302:isolation & purification* / Q000378:metabolism; D006864:Hydrogenase; D008027:Light; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D012247:Rhodospirillum rubrum / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D000596:Amino Acids; D005288:Ferredoxins; D010088:Oxidoreductases; D006864:Hydrogenase